Self-opening die-head



p 1935. c. HAENGGI SELF OPENING DIE HEAD Filed Dec. 29, 1935 Patented Sept. 10, 1935 UNITED STATES ussie PA'IEN'E @FHQE.

Application December 29, 1933, Serial No. 704,584 In Switzerland January '7, 1933 3 Claims.

The object of the present invention is a selfopening die-head in which a divided threading die-plate is secured, the halves of this die-plate having each two or more cutting edges and being pivotally connected together like the jaws of a clamp. The invention resides in the arrangement of a particular pivotal connection of the die-halves for the purpose of a simultaneous and full disengagement of the cutting edges of the die-halves from the screw thread when the diehead is opened. According to the invention the parts of the divided die-plate having each twoor more cutting edges are movably connected together by means of a common pivot or the like situated outside of the plane of symmetry of the die-plate or die-head so as to cause the diehalves or jaws in the opening stroke to have their cutting edges displaced along different curved paths; so that all the cutting edges of the diejaws may be simultaneously and fully disengaged from the screw-thread without it being necessary to impart a too great opening stroke to the die- Jaws.

An example embodying the invention is illus- 2'5' trated in the accompanying drawing.

Figure l is a front elevation,

Figure 2 is a side elevation,

Figure 3 is a plan view and Figure 4 is a longitudinal section thereof;

? Figure 5 is a rear end View of the die-plate carrier;

Figure 6 is a front view of the head body;

Figure '7 is a partial longitudinal section thereof;

Figure 8 is a detail section on line 88 of Figure 1;

Figure 9 is a detail section on line 99 of Figure 1;

Figures 10 and 11 show a modified die-plate.

': As can be seen the die-head shown in Figures 1 to 9 comprises three main parts: a body A, a sliding carrier B and jaws C C with the divided die-plate R.

On the front flanged part of the body A; an

adjusting spindle bearing Ct is mounted and secured by a screw a This flange has in its periphery two inclined bores b (Figure 6) which receive springs t for opening the head. An adjusting spindle c with adjusting nuts (1 serves first for adjusting the head to cut the desired thread diameter, secondly as a fixing device to hold the two die-plate jawsstationary during the working period, and thirdly as a positively entrained stop which when the jaws are closed determines the end position of their closing movement 50 that catch pins it provided thereon cannot slide beyond grooves i but snap therein at such end position.

The adjusting spindle c has right and left hand threads on it cooperating with the respective 5 nuts (1 by the setting of which the head is adjusted to the desired thread diameter. A screw e prevents the spindle c from coming forward out of its carrying groove. By tightening this screw 6 its conical end firmly clamps the spindle 10 c in the desired position in its groove so that the adjusted thread diameter cannot be inadvertently changed.

The carrier 3 slides axially in the body A, but is prevented from rotating by two keys 13 pro- 5 vided on the carrier B and engaging corresponding longitudinal grooves in the body A (Figures 6 and '7). Into the carrier B is screwed a sleeve which under the thrust of a spring g acts to draw the carrier B into the body A. The front 20 of the carrier B is in the form of a flange, at the top of which is milled a flat, which constitutes a sliding fit or guiding seat for the adjustlug nuts (1. This flat together with the body flange abutting at the rear forms a thoroughly 25' stable support for the adjusting nuts (I which cannot therefore yield in any direction} On the flange of the carrier B are pivoted the two jaws C whose common pivot C is set in the flange and so arranged outside of the plane 0 of symmetry of the jaw-set that when the jaws open all cutting edges of the die-plate leave the work as far as possible simultaneously and completely.

Each jaw C carries at its upper end the spring 35 urged catch pin h which is engaged by milled surfaces at its front end in the groove 2 in the corresponding adjusting nut 01 and is prevented from rotating by a tongue lc projecting into a slot in the pin. These tongues k also serve as abutments for 40 the springs Z of the pins it so that when the pins are withdrawn; the springs are compressed and afterwards thrust the pins forward into the grooves 12 when the jaws are closed.

Pins m in the two jaws project rearwardly through slots in the carrier flange and there carry sliding plates 11, working in grooves milled in the back of the flange. These pins and plates can be adjusted by means of screws 13 when the. sliding surfaces become worn after long use. Key 50 pins p engaging in the pins m prevent the latter from rotating during adjustment. This provision for adjustment by which axial play of the jaws can always be taken up enables accuracy of the threads cut to be constantly maintained. 55

The two jaws C have on their inner edges a turned seating with two conical faces q to receive a correspondingly shaped die-plate R formed of two parts, which are separately drawn in and secured in the seating by separate screws 8. By being separately drawn into this conically formed seating the die halves are very firmly held and cannot move axially relative to one another. These die halves do not bear at their bottom on the seating, but sufficient clearance is left here so that they can be properly pressed onto the conical faces. The die halves are each provided with two or more chaser-like cutting edges r.

Opening of the die-head is eifected by the springs 15 which exert pressure on short sleeves sliding in the inclined bores b. Each sleeve carries a laterally projecting pin t which projects some distance through a slot milled in the front wall of the body flange and so far into a bore in the respective sliding pin m that it still has sufficient engagement therein with the carrier B withdrawn i. e. slid forward. Closing of the jaws loads the springs t and when the catch pins h are drawn out of the grooves i the springs t thrust the jaws apart.

To bring the die-head into operative position, handles V upon the jaws are pressed towards one another. The spring urged catch pins h then slide along inclined surfaces on the adjusting nuts it until they snap into the grooves 2'. They cannot slide further because the inner wall of the grooves is higher than the inclined surfaces in advance of the grooves (Figure 8). This projecting wall is a stop automatically set by every change of adjustment for the proper position of the jaws.

Once the pins it have snapped into their grooves 2' the head is ready for use. It is secured upon the saddle of the machine upon which the screws are to be cut, the saddle then brought up to the work piece and gently pressed against it until the die starts to cut. The saddle is then fed forward until upon reaching the desired length of thread it comes against a stop.

The front part of the head (jaws C and carrier B) is now drawn forward by the work piece until the pins h are drawn out of the grooves i whereupon the jaw halves are instantly opened by the springs t and the head can be directly withdrawn over the work piece.

If the springs t or pins t should by chance fail or break, when the slide carrier and jaws are drawn forward, the jaws are sufficiently opened by inclined surfaces to on the grooves 2' and pins h to take the cutting teeth out of the cut thread and the head can be withdrawn without damaging the die-head or the work piece.

By pressing the handles V towards one another the head is brought into position for a further working cycle.

Instead of by hand, the closing of the handles or jaws can be effected automatically if the head is to be used upon an automatic screw making machine or the like.

The sleeve f has a shoulder f at its rear end to limit the sliding movement when the carrier is drawn forward, so that the pins 25 cannot be drawn right out of engagement with the sliding plates n or pins m.

To avoid the chip holes or spaces between the cutting edges from becoming temporarily choked with chips, which would involve interruption in work for removal of the jammed chips, according to the modification shown in Figures 10 and 11, the cutting edges 1 of the die-halves are each provided with an inclined groove or flute r so arranged that the curling chips are positively turned outwards and can no longer collect in the holes or spaces.

In making these inclined grooves however, the height of the cutting edge must not be changed over its length, that is not lowered at the leading end. Grinding down of the leading cutting edges below the level of those behind would result in the head no longer opening automatically because an inclined cutting edge would cause the die-halves to grip the threads.

What I claim is:

1. A self-opening die-head, comprising a main body, a sliding carrier thereon, movable jaws mounted on said carrier, common pivotal interconnecting means for said jaws outside of the plane of symmetry thereof, a divided threading die-plate with several cutting edges on each part and having its parts symmetrically mounted on said jaws, controlling means between the latter and the carrier to cause through sliding thereof the automatic opening of the die-jaws, said interconnecting pivotal means being so arranged as to cause said die-jaws in opening stroke to have their cutting edges displaced along different curved paths for simultaneous and full disengagement thereof.

2. A self-opening die-head, comprising a main body, a sliding carrier thereon, movable jaws mounted on said carrier, a divided threading dieplate with several cutting edges on each part and having its parts mounted on said jaws, a rotatable regulating right and left hand threaded spindle on the main body and two adjusting nuts on said spindle having, on the one hand, stop parts for cooperating with corresponding parts on the die-jaws to determine their end position on their closing movement and, on the other hand, cam surfaces for cooperating with corresponding surfaces on the die-jaws to determine opening thereof responsive to sliding of the carher.

3. A self-opening die-head, comprising a main body, a sliding carrier thereon, movable jaws mounted on said carrier, a divided threading die-plate with several cutting edges on each part and having its parts mounted on said jaws, a rotatable regulating right and left hand threaded spindle on the main body and two adjusting nuts on said spindle having stop parts with cam surfaces, two axially movable spr ng urged pins on the die-jaws having corresponding parts to cooperate with said stop parts with cam surfaces on the nuts to determine the end position of the jaws on their closing movement as well as their opening response to sliding of the carrier.

CARL HAENGGI. 

